That can be found x times in the sticky threads of the Multi-media sub-forum here.
Either YaST > Software > Software Management > from the View choose Repositories > select Packman repo at left, at right you get the list of packages and above that is something like Switch system packages to … > click that and Continue.
zypper dup --from <Packman>
where you replace by the Alias, Name or Number from your Packman repo entry to be found in
As you can see from @hui’s post it is all about patents and licenses. As openSUSE was always related to a larger commercial company, that company can be held liable for not observing the patents/licences.
But Packman is an organisation with no money, thus bringing Packman to court is not likely to bring any profit.
BTW sometimes a patent expires (IIRC e.g. mp3). From that point on Packman will stop providing the codecs and full support will be direct in the OSS repo. The result might be a bit confusing because a vendor change back is to be made.
Your guess is wrong.
One of the most used mirrors is at gwdg.de which is Gesellschaft für wissenschaftliche Datenverarbeitung mbH, which is based in Göttingen, Germany. And there are other mirrors in Europe.
I assume everyone of them has it’s own details. So go and investigate.